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Saturday, May 05, 2018

Seven months ago, I talked about how we were trying a bokashi composting system to deal with food waste, the stuff that can’t normally be composted. I said at the time I’d do a follow-up post to talk about this experience. This is that post, and the short version is: We found how to make it work. Here’s what we learned.

The first thing that most people want to know about is the smell: Does a bokashi bin stink? Honestly, that kind of depends on what smells one finds bad. Ordinarily, the bin smells kind of like vinegar because it ferments the contents. It’s not a particularly strong smell, but it’s noticeable.

However, there have been two times in which the bin smelled kind of like a wet ashtray—like cigarette ash, the paper, butts, unused tobacco and water all mixed together. That seems to be caused by a kind of fungus growing in the drainage water, and that seems to have been caused by putting in stuff that was too wet to begin with. The contents of the bin haven’t smelled like that, but the vinegar smell was weaker, which can be a sign the bin isn’t working at peak efficiency.

The lesson learned: Try not to put excess water into the bin. It may help to wash the bucket everything drains into, but that’s extra work. Rinsing it with plain water does help a bit.

The ill-fated trench.

The original instructions said to leave the bin sealed for ten days, then put it in your regular compost bin or bury it in a trench. When the first bin was ready, we didn’t have a usable compost bin, though we were planning to buy one (as I mentioned in the post last September). So, I dug a trench and dumped the bin into it (photo at left).

Re-dug trench.

Trouble is, the dogs (especially Sunny) dug it up to eat it (which I mentioned on Instagram, but not here). So, I covered it up, put an old metal truss and rocks on top. Sunny managed to dig up parts of it again (photo at left). Clearly, that wasn’t going to work.

So we bought a rotating compost bin (photo bottom left). It rotates by hand after you release a pin on the right hand side (not visible in the photo). We dug up the ill-fated trench and placed it in the bin, and I added some garden weeds—ordinary compostable stuff. But the bin was very heavy to rotate due to all the dirt.

The next bin was 15 litres (the only size the store sold), so it took a long time to fill. When it was time to head off for our Australia trip, the bin was about ready to sit for the ten days. But we didn’t want anyone else to have to empty the drainage bucket while we were away. So, I put it outside without its drainage bin. I put it on some bricks, surrounded it with heavy things, and hoped the dogs wouldn’t get to it. They didn’t, and I was able to dump the contents in the rotating compost bin.

A few weeks later, it was getting time to empty yet another bin, but we decided to empty the compost bin first. So, I wheeled it over to the same area where we’d dumped the first bokashi bin weeks earlier, and dumped it out. It looked like dirt, with a few sticks, a couple egg shells, and some tea bags. All the other stuff had successfully composted, including the contents of those tea bags. Most of the stuff had been in there about three months, the last bokashi maybe six weeks. This was in summer, when composting works much faster.

Since then, our use of the bokashi bin has slowed, mostly because we haven’t been having as many salads as the weather has cooled, so there’s been less going into the bin. Even so, we did add one more bokashi bin to the rotating bin, and that one stank. This was probably a sign the bokashi didn’t work correctly. I added some leaves and garden weeds and it was a little better, but not much. I recently added more garden waste, but the bin seems to be too wet, possible due to all the storms we’ve had recently. I need to add more dry matter.

With winter fast approaching, and the inevitable slowing of the composting process, it’ll now take a lot longer for things to break down in the compost bin. How much longer, however, is something we’ll still have to learn.

This hasn’t been easy, and I have reservations about it all. First, it’s work to put things in the bin and drain the drainage bucket. Then, there are the times it smells. The bokashi bin we currently have smells okay, but the drainage bin smells like a wet ashtray. If the finished bokashi smells bad, that will mean that two of the bins have been perfect, two have not. That’s actually not a very good average. I should add that they’ve all been handled identically, and I think, but am not sure, that they have had pretty much the same stuff put into them, apart from tea bags, since we don’t put those in any more.

We stopped putting in teabags because, as I said earlier, some emerged from the compost bin intact (though without their contents). The thing is, there were far fewer survivors than there were teabags used. We use two different kinds of tea, so my guess is that either some bags randomly composted and others didn’t, or else one kind of teabag composted and the other kind didn’t (I’m leaning toward this explanation). I could experiment to find out.

The whole reason we started this system is that a bokashi allows people to compost food waste that normally can’t (or shouldn’t) be composted, such as, meat (raw or cooked), cheese, baked goods (like spoiled bread, for example, or dried out cake), that sort of thing. But we don’t eat much meat any more, and don’t have leftover raw or cooked meat when we do, and cheese never last long enough to become compost fodder. So, maybe the bokashi is no longer necessary, and everything we have can now go into the regular compost bin. This is a distinct possibility, and one I need to think about a bit more.

Auckland Council is starting free collection of Council-provided food waste wheelie bins (they're quite small, really) because, I’m told, about 40% of the rubbish sent to landfills in Auckland is compostable food waste (I presume that means by weight, not volume). The new system will eventually roll out to our area, and when it does, I may stop using the bokashi (if I haven’t already) because of the problems I mentioned, and because it’d be easier. But, then, we do have a good compost bin now, and it wouldn’t be any harder to put things in there regularly. I suppose I’ll eventually need another update.

So, for now, we’ll continue to use the bokashi to compost food waste. I can’t be sure we’ll keep using it long term, though.